Mitsubishi FA20S Issues
Close
Login to Your Account
Results 1 to 6 of 6
  1. #1
    Join Date
    Feb 2019
    Country
    POLAND
    Posts
    1
    Post Thanks / Like
    Likes (Given)
    0
    Likes (Received)
    1

    Default Mitsubishi FA20S Issues

    Hello Guys!

    I've got couple questions I would love to hear some answers to. About 6/7 months ago I've took over 3 WEDMs at my new workplace , they were very poorly maintained and slowly but surely I'm bringing them back to former glory (mainly with lots of cursing and throwing wrenches at them, just kidding) but today one of them (FA20S - 2008 production) decided to fail me and completely lost pressure when threading the wire, I mean by that 0 pressure at lower and upper head. The water just drips like my tears.

    My first guess is that a Solenoid valve has failed and its no longer supplying air pressure but its just a single guess and I would appreciate some more guesses/advices what can be the cause of this behaviour.

    Also I'm finding a need to calibrate wire alignment on this machine preety often, by that I mean once a week. 80/85% of parts I make drown in tolerances of +/-0.01 mm and tighter and the usual U/V movement over the week hangs around 0.01-0.015 mm. Is it to be expected from 11 year old machine that was neglected ? Are there any remedies that I can use to counter that?

  2. Likes msrbl liked this post
  3. #2
    Join Date
    Dec 2018
    Country
    HUNGARY
    Posts
    29
    Post Thanks / Like
    Likes (Given)
    4
    Likes (Received)
    2

    Default

    Well, about the water thing, i cant help you right now, but the alignment issue is a pretty common thing (i guess), 0.01-0.015 mm is not really a big thing, it is present on both of our FA20s machines. To be honest, if we do the aligning process twice in a row, the U-V axes will always move around 0.01 mm. It's the accuracy of the align cycle or the machine, i guess. If the wire is far from being completely perpendicular, after you align it, then maybe your align bock is bad in some way. If your alignment goes away after some time, your glass scales can be bad. On our newer machine they are disabled completely (the U-V only). We never had an issue, or at least not related to this.

    Also, i think these machines can't make very tight tolerances for the first try. We tried everything we could. Maybe we got the best result, when we set the PM to "optimal condition", but in most cases (at least for us) this option is out of the question, because the heads are too far away from the top of the surface we want tu cut. If you can move with the heads close as possible, set the height right in the power master, turn on the straightness compensation, then you should be able to cut those tolerances. On the parts you cut out, you can make it fit the tolerances by default (mostly), but with holes, it's a harder task (for us at least). In some cases, we have to run the 3rd and/or 4th cuts again, to make them fit, but altering the H variables is a good approach too. These machiner are great if you have to make a lot of the same part, but if all of your pieces are unique, you have to deal with this. Even a local service could not make this better. ...Or we are incompetents. We have spoken to other people, who use similar mitsubishi machines, they too have this issue. The newer models are improved a bit, but the FA-S series we use seems to have this issue, and noone has a solution that i know of. If someone knows how to deal with this, i'm intrested too.

    Balint

  4. #3
    Join Date
    Dec 2015
    Country
    UNITED STATES
    State/Province
    Ohio
    Posts
    78
    Post Thanks / Like
    Likes (Given)
    29
    Likes (Received)
    21

    Default

    Quote Originally Posted by veiszb2 View Post

    Also, i think these machines can't make very tight tolerances for the first try.

    Balint

    You have to do multiple skim cuts to get good accuracy along with a good surface finish. EVERY brand wire edm I have ever used this was necessary.
    Yes you can compensate with the variables or your offset to get you close to what you want but it will never be as good as using finishing passes.
    Yes, it takes extra time..wire edm is not a fast process.


    OP, you are more than likely a solenoid, make sure you ready/power off the machine before servicing these. Personally I would just clean all of them there are only 12.

  5. Likes msrbl liked this post
  6. #4
    Join Date
    Dec 2018
    Country
    HUNGARY
    Posts
    29
    Post Thanks / Like
    Likes (Given)
    4
    Likes (Received)
    2

    Default

    Sorry, I meant that even with 4 cuts (1 rough 3 skim) our machines fail to cut the holes we need for the first try. the second or third hole will be way better (with altered settings), but the first is almost never good enough. If we progrm it to do a 10x10 mm square hole, it will make 9.95-9.97 sized hole. That is also true, if we cut circles. These machines, that we own siply can't make these dimensions on default settings. I don't know why is that, our Agie Chllange 2 from the year 2000 do it way better. These Mits machines are way younger (2006 and 2011) and both of them have them does this. We maintain them regularly, and their ballscrews are fine, as far as i know.

  7. #5
    Join Date
    Dec 2015
    Country
    UNITED STATES
    State/Province
    Ohio
    Posts
    78
    Post Thanks / Like
    Likes (Given)
    29
    Likes (Received)
    21

    Default

    Quote Originally Posted by veiszb2 View Post
    Sorry, I meant that even with 4 cuts (1 rough 3 skim) our machines fail to cut the holes we need for the first try. the second or third hole will be way better (with altered settings), but the first is almost never good enough. If we progrm it to do a 10x10 mm square hole, it will make 9.95-9.97 sized hole. That is also true, if we cut circles. These machines, that we own siply can't make these dimensions on default settings. I don't know why is that, our Agie Chllange 2 from the year 2000 do it way better. These Mits machines are way younger (2006 and 2011) and both of them have them does this. We maintain them regularly, and their ballscrews are fine, as far as i know.

    So on this 10x10 mm square, how thick is the material? What Epacks are you using and what are your offsets and wire size and type?

  8. #6
    Join Date
    Dec 2018
    Country
    HUNGARY
    Posts
    29
    Post Thanks / Like
    Likes (Given)
    4
    Likes (Received)
    2

    Default

    It was just an example. Right now we cutting a 40mm thick 1.2343 piece, that's 14mm above the lower head and about 15-18 mm bellow the upper. The D8H7 hole is 0.03mm smaller. We use simple brass .25 wire, with the default standard (2041-2042-2043-2044, with the H offsets 0.232, 0.179, 0.143 and 0.130) epacks. We left the power master on variable condition (otherwise the wire breaks) and the adaptive control enabled. We tried both the direct cut methond and the coreless, but both making the same size. When the guys from Austria were here, they tried those methods too, nothing worked. I believe that eighter both of our machines are bad, or we (and other near companies) are using some messed up settings, or these machines are simply can't do this kind of work on the desired accuracy.


Tags for this Thread

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •